ORNL/TM-2015/466

Q-Sync Motors in Commercial Refrigeration: Preliminary Test Results and Projected Benefits

Brian A. Fricke Bryan R. Becker

September 2015

Approved for public release. Distribution is unlimited.

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ORNL/TM-2015/466

Building Technologies Research and Integration Center

Q-SYNC MOTORS IN COMMERCIAL REFRIGERATION:

PRELIMINARY TEST RESULTS AND PROJECTED BENEFITS

Brian A. Fricke

Bryan R. Becker*

Date Published: September 2015

Prepared by

OAK RIDGE NATIONAL LABORATORY

Oak Ridge, Tennessee 37831-6283

managed by

UT-BATTELLE, LLC

for the

US DEPARTMENT OF ENERGY

under contract DE-AC05-00OR22725

* University of Missouri – Kansas City, 5100 Rockhill Road, Kansas City, MO 64110-2499

iii

CONTENTS

Page

LIST OF FIGURES ...................................................................................................................................... v LIST OF TABLES ........................................................................................................................................ v ACRONYMS .............................................................................................................................................. vii ACKNOWLEDGMENTS ........................................................................................................................... ix ABSTRACT ................................................................................................................................................. xi 1. INTRODUCTION: EXISTING 9–12 WATT EVAPORATOR FAN MOTOR

TECHNOLOGIES ................................................................................................................................ 1 2. THE NEW Q-SYNC MOTOR TECHNOLOGY ................................................................................. 3 3. EVAPORATOR FAN MOTOR FIELD DEMONSTRATION AND PRELIMINARY

RESULTS ............................................................................................................................................. 5 4. POTENTIAL SITE AND SOURCE ENERGY SAVINGS ................................................................. 7

4.1 SITE ENERGY SAVINGS ......................................................................................................... 7 4.2 SOURCE ENERGY SAVINGS ................................................................................................. 9

5. EFFECTS OF FAN MOTOR POWER FACTOR.............................................................................. 11 6. CONCLUSIONS ................................................................................................................................ 13 7. REFERENCES ................................................................................................................................... 15

v

LIST OF FIGURES

Figure Page

Figure 1. Performance of EC and Q-Sync fan motors before and after retrofit: (a) current, (b) power........ 5

LIST OF TABLES

Table Page

Table 1. Characteristics of evaporator fan motors ........................................................................................ 7 Table 2. Installed base of 9–12 W evaporator fan motors ............................................................................ 8 Table 3. Baseline distribution of evaporator fan motors and total site energy consumption ........................ 9 Table 4. Annual source energy consumption and savings for baseline and Q-Sync fan motors ................ 10 Table 5. Annual source energy consumption of fans in residential and commercial buildings ................. 14

vii

ACRONYMS

AC alternating current

BTO Building Technologies Office, US Department of Energy

DC direct current

DOE US Department of Energy

EC electronically commutatedr

M&V measurement and verification

NCI Navigant Consulting Inc.

ORNL Oak Ridge National Laboratory

PNNL Pacific Northwest National Laboratory

PSC permanent split capacitor

ix

ACKNOWLEDGMENTS

This report and the work described were sponsored by the Commercial Buildings Integration

program within the Building Technologies Office of the US Department of Energy Office of

Energy Efficiency and Renewable Energy. The authors wish to acknowledge the contributions of

Amy Jiron and Charles Llenza in guiding this work and the insightful review comments of

Vishaldeep Sharma of ORNL. This work would not have been possible without the excellent

support of lab technicians Geoffrey Ormston, Randy Linkous, and Tony Gehl.

xi

ABSTRACT

The US Department of Energy Building Technologies Office (DOE BTO) estimates that the

commercial sector uses approximately 18% of all primary or source energy consumed in the United

States, or 17.3 quadrillion Btu (quads) (1 quad = 1015

Btu) (NCI 2013). “Primary” or “source” energy

refers to the sum of the energy consumed at the site (site energy) plus the energy required to extract,

convert, and transmit that energy to the site, and “site” energy refers to the energy directly consumed at

the site, typically measured with utility meters (Deru and Torcellini 2007). The DOE estimates that the

conversion from site to source electric energy is 3.16 units of source energy per unit of site energy ( DOE

2011). Therefore, the 17.3 quads of primary energy consumed by the US commercial sector equates to

approximately 5.07×1012

kilowatt hours (kWh) of primary energy (1 Btu = 2.931×10−4

kWh), which in

turn converts to 1.60×1012

kWh of site energy, valued at approximately $170 billion (EIA 2015)2.

Of that 17.3 quads of primary energy, DOE BTO estimates that the primary energy consumption of

electric motor-driven systems in the commercial sector is 4.87 quads and that the motors in central

commercial refrigeration and beverage vending machines account for 6.7% and 3.6% of that 4.87 quads,

respectively (NCI 2013). This equates to approximately 96×109 kWh of primary energy for central

commercial refrigeration, which in turn converts to 30×109 kWh of site energy, valued at approximately

$3.2 billion. For beverage vending machines, this equates to 52×109 kWh of primary energy, which in

turn converts to 16×109 kWh of site energy, valued at approximately $1.7 billion.

Although higher-efficiency motors have been increasingly used in central commercial refrigeration

and beverage vending machines, the installed base of smaller 9–12 W evaporator fan motors continues to

be dominated by lower-efficiency shaded-pole motors. Over the past 10 years, the higher-efficiency

electronically commutated (EC) motor has begun to penetrate the market. While EC motors are

significantly more efficient than shaded pole motors, QM Power Inc.’s newly available, UL approved Q-

Sync motors offer even greater efficiency at a comparable first cost. In addition to transforming electrical

energy into mechanical energy more efficiently than EC motors, Q-Sync motors have much higher power

factors, meaning that they accept energy from the grid much more efficiently. The resulting reduced

current draw means that the electric utility can reduce the amount of energy that it needs to supply to the

grid.

This report provides background information on various fractional-horsepower electric motor

technologies, summarizes initial data from a DOE-sponsored Q-Sync motor demonstration project, and

extrapolates that data to project the potential economic and environmental benefits resulting from

upgrading the current installed base of 9–12 W evaporator fan motors to Q-Sync motors.

2 The Energy Information Administration reported that the average commercial electricity rate was 10.58 cents per

kilowatt-hour during the first quarter of 2015 (EIA 2015). This price will be used throughout this report in

translating kilowatt-hours used/saved to dollars at the motor level.

1

1. INTRODUCTION: EXISTING 9–12 WATT EVAPORATOR FAN MOTOR

TECHNOLOGIES

Evaporator fan motors are a fractional horsepower in size, are responsible for moving air across the

evaporator coil, and typically run at one speed. The manufacturer will match the motor size and blade to

the evaporator coil to meet the expected load on the case under most conditions. Higher-efficiency

evaporator fan motors reduce energy consumption by requiring less electrical power to generate the same

motor shaft output power (NCI/PNNL 2011).

Historically, shaded-pole motors have been the most commonly used evaporator fan motors in

commercial refrigeration equipment and beverage vending machines. The shaded-pole motor, a type of

single-phase AC induction motor, is the simplest and least expensive type of fractional-horsepower

motor. It is also the least efficient in terms of converting electrical energy into mechanical energy. The 9–

12 W sizes commonly used for evaporator fans in these systems are typically 20% efficient (NCI/PNNL

2011). Given that motor efficiency losses are released as heat, this inefficiency also increases the

refrigeration load, further decreasing overall refrigeration system efficiency.

Electronically commutated (EC) motors, also known as brushless DC motors, were conceived in 1962

(Wilson and Trickey 1962) and first became widely commercialized in the late 1980s, after higher-quality

rare-earth permanent magnets became more readily available (de Almeida and Greenberg 2004). The use

of these premium-priced EC motors for commercial refrigeration fan applications began in earnest 10 to

15 years ago, and their use has increased because of economic incentives and regulatory requirements.

Another motor type, the permanent split capacitor (PSC) motor, which holds a limited share of the

market, offers a mid-point between shaded-pole and EC motor price and efficiency levels. The

Department of Energy (DOE) reports that for commercial refrigeration evaporator fan motor applications,

state-of-the-art EC motors are 66% efficient and PSC motors are usually about 29% efficient

(NCI/PNNL 2011).

All electric motors function as converters of electrical energy to magnetism and then to mechanical

rotating motion. The operation of all electric motors is based on the interaction between a field magnet

and a magnetic rotor. The electromagnetic interactions between these two magnets cause the rotor to

rotate. The different types of motors result from the manner in which the rotating magnetic fields are

generated.

In an induction motor, the AC current is fed into the stator coil, which creates a rotating magnetic

field around the stator. This rotating magnetic field in the stator induces a current in the rotor coil, which

in turn, generates a magnetic field around the rotor. The magnetic fields of the rotor and stator interact. As

the magnetic field in the stator rotates, the rotor follows it and torque is generated.

Single-phase induction motors suffer from a serious shortcoming in that they only produce an

interaction of two rotating magnetic fields when the rotor is rotating. Simply powering the electromagnet

is not sufficient to start such a motor. One of the most significant differences among various types of

single-phase induction motors is the way they handle this start-up problem (NCI/PNNL 2011).

Nearly all inexpensive fan motors are either shaded-pole or PSC induction motors. In a shaded-pole

motor, a shading ring, typically a single short-circuited turn of thick copper, surrounds one side of the

stator poles. Most of the magnetic flux from the stator crosses the air-gap to the rotor. However, a small

portion of the flux passes through the shading ring and induces a current in the ring. The resulting

magnetic flux in the ring reaches a peak after the main flux, thereby producing a rotation of the flux

across the face of the stator poles. This shift in the flux across the face of the stator poles is required to

start the motor. Incidentally, the side of the stator poles where the shading ring is placed dictates the

direction of rotation of the motor (Hughes and Drury 2013). Because a portion of the electrical energy

input is used to induce the magnetic field of the shading ring, and since the imbalance between the shaded

and unshaded portions of the stator poles remains throughout operation, shaded-pole motors are

inefficient.

2

In a PSC motor, a smaller start-up winding is present in addition to the main stator winding. The start-

up winding is electrically connected in parallel with the main stator winding and in series with a

capacitor, which causes a phase-shift of the current in the two windings. At startup, the interactions

between the magnetic field generated by the start-up winding and that generated by the main winding

create a rotating magnetic field that induces rotation of the rotor. As the motor reaches steady state, the

start-up winding becomes an auxiliary winding, thereby approximating two-phase operation at the rated

load point. For that reason, PSC motors are more energy efficient than their shaded-pole counterparts

(NCI/PNNL 2011).

The EC motor, also known as the brushless permanent magnet motor, is more energy efficient than

either shaded-pole or PSC motors. In the EC motor, the grid-suppled AC current is rectified to DC

current. The stator is composed of individual windings. The DC current to these windings is electronically

commutated (switched) by digital signals from simple rotor position sensors. As the DC current is

switched to the various stator windings, a rotating magnetic field is created. This rotating magnetic field

creates a torque by pulling the permanent-magnet rotor. This combination permits the motor to develop a

smooth torque, regardless of speed (de Almeida and Greenberg 2004).

3

2. THE NEW Q-SYNC MOTOR TECHNOLOGY

QM Power Q-Sync motors are designed to be superior to EC motors, as well as shaded-pole and PSC

motors. The Q-Sync motor is a permanent magnet synchronous AC motor that can directly use grid-

supplied AC current without the need to rectify to DC. Synchronous motors are so named because the

rotation of the motor’s shaft is synchronized with the frequency of the supplied current. Previously,

synchronous motors have been prohibitively expensive for commercial refrigeration evaporator fan

applications because of the high cost of the electronic control circuit that is required to bring the

synchronous motor up to synchronous speed. However, Q-Sync’s novel, patent-pending controller is

simpler and lower in cost than previous synchronous motor controllers or EC motor controllers, making

the Q-Sync motor a cost-effective alternative in the commercial refrigeration market.

The QM Power Q-Sync motor technology includes a split-wound stator coil as well as a motor

controller with a Hall effect sensor to detect rotor position. Upon startup, or when the Hall effect sensor

detects that the motor is not running at synchronous speed, the motor controller modifies the frequency of

the AC current delivered to the stator coil to bring the motor to synchronous speed. When the frequency

detected by the Hall effect sensor matches the frequency of the input AC, the motor is running

synchronously. If the motor is running synchronously, the motor controller is not needed and is switched

off until either the motor falls out of sync or the motor is stopped and restarted. If the motor slows below

synchronous speed, then the motor controller will control the motor timing as it does for startup. Using

this method improves overall motor efficiency and the expected lifetime of the components in the circuit

(Flynn and Tracy 2014).

As a result, Q-Sync motors use less energy to provide the same power output, compared with EC and

shaded-pole or PSC motors. Since the Q-Sync motor is a permanent magnet motor, it requires less current

than an induction motor to produce the same power because no magnetizing current is necessary.

Furthermore, compared with an EC motor, the Q-Sync motor does not need to rectify AC to DC, thereby

eliminating power-consuming electronics. Moreover, because they can use AC power directly from the

grid, Q-Sync motors have much higher power factors than EC motors. While the superior power factor

does not mean that the motor uses less power on site, it does mean that the utility is able to supply less

power to the grid per unit of output of the motor. Another inherent advantage of Q-Sync motors is that the

field coils are energized before the electronic controller, thereby protecting the electronics against power

surges. Finally, the elimination of the electronics from the circuit while the motor operates at synchronous

speed is expected to increase the reliability and service life of Q-Sync motors.

4

5

3. EVAPORATOR FAN MOTOR FIELD DEMONSTRATION AND PRELIMINARY

RESULTS

QM Power Inc. was recently awarded a DOE grant to support a field demonstration project to

quantify the energy savings realized by switching from shaded-pole, PSC, or EC evaporator fan motors to

Q-Sync motors. Oak Ridge National Laboratory (ORNL) is responsible for measurement and verification

(M&V) in this project. The M&V plan consists of side-by-side measurement of the power consumption of

Q-Sync and shaded-pole, PSC, or EC evaporator fan motors in identical refrigerated display cases. The

M&V plan includes provisions for measuring fan motor power, current, and power factor, as well as

display case discharge and return air temperatures and ambient store temperature.

The first such side-by-side comparison has begun in a 16 ft medium-temperature vertical multi-deck

refrigerated display case at a Hy-Vee Supermarket located in the Kansas City metropolitan area. Before

this side-by-side comparison, the display case contained four 12 W EC evaporator fan motors, two in each

8 ft section. At the onset of this comparison, the two existing EC motors in one of the 8 ft sections were

replaced with two 12 W Q-Sync motors. Thus, at this test site, two 12 W Q-Sync motors are being

compared with two existing 12 W EC motors.

The initial results reveal that the Q-Sync motors offer a significant advantage over the existing EC

motors. On average, the Q-Sync power consumption is 27.4% lower (32.8 versus 45.2 W); and the current

draw is 53.3% lower (0.292 versus 0.625 A). Assuming a total motor output of 24 W (each display case

has two 12 W fan motors) implies that the Q-Sync motor efficiency is 73.1% versus the EC motor

efficiency of 53.1%. In addition, the power factors are 0.936 for the Q-Sync motors and 0.601 for the EC

motors. Graphs depicting the changes in power and current draw before and following the motor retrofit

can be seen in Figure 1.

Figure 1. Performance of EC and Q-Sync fan motors before and after retrofit: (a) current, (b) power.

6

7

4. POTENTIAL SITE AND SOURCE ENERGY SAVINGS

Using the preliminary test data discussed above, the potential site and source energy savings

associated with retrofitting the existing installed base of 9–12 W commercial refrigeration evaporator fan

motors with Q-Sync fan motors can be estimated.

4.1 SITE ENERGY SAVINGS

For purposes of comparison, a baseline must be established. This baseline includes performance

characteristics for the current installed base of evaporator fan motor types, as well as statistics regarding

the installed base of commercial refrigeration evaporator fan motors.

The characteristics of various types of evaporator fan motors are given in Table 1. The motor

efficiencies of shaded-pole and new EC motors were obtained from NCI/PNNL (2011). The motor

efficiencies and power factors of the old EC and Q-Sync motors were obtained from the preliminary test

data discussed in Section 3. The power factor of shaded-pole motors and new EC motors was assumed to

be 0.601, which is the value measured for the old EC motors discussed in Section 3. Output power for all

motors was assumed to be 12 W. For the old EC motors and Q-Sync motors, input power was measured

as discussed in Section 3; and for the shaded-pole and the new EC motors, the input power was calculated

from the assumed output power and motor efficiency. It was assumed that all evaporator fan motors in

commercial refrigeration equipment and beverage vending machines operated continuously for 8760

hours per year.

Table 1. Characteristics of evaporator fan motors

Table 2 provides details of the number of installed 9–12 W evaporator fan motors. Based on a survey

of the installed base, it is estimated that there are approximately 15.8×106 evaporator fan motors installed

in commercial refrigeration equipment and beverage vending machines. Facility count information was

obtained from Progressive Grocer (2015), the Association for Convenience and Fuel Retailing (NACS

2015), the National Restaurant Association (NRA 2015), IBIS World (2015) and Statistic Brain (2015),

and the number of motors per facility was estimated based on discussions with industry partners.

Motor type

Motor

efficiency

(%)

Power

factor

Output

power (W)

Input

power (W)

Application: Commercial Refrigeration Equipment

Shaded-polea 20.0 0.601 12 60.0

EC motor, oldb 53.1 0.601 12 22.6

EC motor, newa 66.0 0.601 12 18.2

Q-Syncb 73.1 0.936 12 16.4

Application: Beverage Vending Machines

Shaded-polea 20.0 0.601 12 60.0

EC motor, oldb 53.1 0.601 12 22.6

EC motor, newa 66.0 0.601 12 18.2

Q-Syncb 73.1 0.936 12 16.4

a Source: NCI/PNNL (2011).

b Source: Preliminary test data discussed in Section 3.

8

Table 2. Installed base of 9–12 W evaporator fan motors

Facility type Facility count Motors per

facility

Total motors

installed

Supermarkets (sales greater than $2 million)

Supermarket (conventional)a 26,487 225 5,959,575

Supercenter (grocery and mass

merchandise)a 4,150 175 726,250

Supermarket (limited assortment)a 3,242 50 162,100

Supermarket (natural/gourmet)a 3,144 70 220,080

Warehouse grocerya 523 100 52,300

Military commissarya 170 225 38,250

Other Food Retail Formats

Conventional convenience storeb 152,794 7 1,069,558

Gas station/kioska 22,303 2 44,606

Superettea 13,070 2 26,140

Conventional cluba 1,320 2 2,640

Military commissarya 674 6 4,044

Other Retailer Categories

Drug storeb 41,799 8 334,392

Dollar storeb 26,572 12 318,864

Restaurants/Bars

Restaurantc 1,000,000 4 4,000,000

Bar/nightclubd 70,016 4 280,064

Beverage Vending Machinese 2,598,400 1 2,598,400

TOTAL 15,837,263 a Source: Progressive Grocer (2015). b Source: NACS (2015). c Source: NRA (2015). d Source: IBIS World (2015). e Source: Statistic Brain (2015).

Table 3 shows the assumed distribution of motor types for the existing installed base of evaporator

fan motors for each application listed in Table 2. This assumed distribution was estimated based on

discussions with industry partners.

Table 3 also shows the total annual site electrical energy consumption of these fan motors. As shown

in Table 3 for the baseline case, it is estimated that 7.2×109 kWh (0.024 quad) per year of site electricity

is consumed by the existing installed base of 9–12 W evaporator fan motors. Assuming the cost of

electricity is 10.58 cents per kilowatt-hour (EIA 2015), this translates into $757 million. Also, assuming

carbon dioxide equivalent emissions of 1.67 lb of CO2 per kilowatt-hour of electricity delivered (Deru and

Torcellini 2007), the CO2 emissions associated with the currently installed base of evaporator fan motors

is estimated to be 12×109 lb.

9

Table 3. Baseline distribution of evaporator fan motors and total site energy consumption

Motor type by

application

Percentage of

installed base

(%)

Annual site

electrical energy

consumption

(kWh/year)

Supermarkets

Shaded-pole 65 2,445,648,730

EC motor, old 30 425,385,699

EC motor, new 5 57,008,129

Other Food Retail Formats

Shaded-pole 85 512,428,359

EC motor, old 15 34,078,965

EC motor, new 0

Other Retail Categories

Shaded-pole 75 257,513,515

EC motor, old 20 25,879,130

EC motor, new 5 5,202,293

Restaurants and Bars

Shaded-pole 90 2,024,641,475

EC motor, old 10 84,778,656

EC motor, new 0

Beverage Vending Machines

Shaded-pole 90 1,229,147,136

EC motor, old 10 51,468,590

EC motor, new 0

TOTAL 7,153,180,677

If all currently installed fan motors were retrofitted with Q-Sync fan motors, the total site electricity

consumption would be estimated at 2.3×109 kWh per year. This represents a site energy savings of

approximately 68%, or 4.9×109 kWh/year (0.017 quad/year), resulting in an annual cost savings of

$516 million compared with the base case. Furthermore, Q-Sync motors are estimated to reduce the

annual CO2 equivalent emissions by approximately 8.1×109 lb compared with the baseline.

4.2 SOURCE ENERGY SAVINGS

Based on the site energy analysis presented, the potential source energy savings associated with

retrofitting existing 9–12 W commercial refrigeration evaporator fan motors with Q-Sync fan motors can

be estimated. Recall that “source energy” refers to the sum of the energy consumed at the site (site

energy) plus the energy required to extract, convert, and transmit that energy to the site, whereas “site

energy” refers to the energy directly consumed at the site (Deru and Torcellini 2007). Furthermore, DOE

estimates that the conversion from site to source electric energy is 3.16 units of source energy per unit of

site energy (DOE 2011).

The site and source energy consumption and potential energy savings for the Q-Sync fan motor

retrofit scenario discussed are given in Table 4. This table gives the source energy consumption for the

baseline case of installed commercial refrigeration evaporator fan motors, as well as the source energy

consumption and savings for a retrofit consisting entirely of Q-Sync fan motors.

The source energy consumption of all electric motors in central commercial refrigeration and

beverage vending machines is approximately 147×109 kWh per year, or 0.50 quad per year (NCI 2013). If

all currently installed evaporator fan motors were replaced with Q-Sync fan motors, the total source

energy attributed to all electric motors in central commercial refrigeration and beverage vending

machines could be reduced to 0.45 quad/year, representing a savings of 10%.

10

Table 4. Annual source energy consumption and savings for baseline and Q-Sync fan motors

Installed base

Annual site electrical

energy consumption

(kWh/year)

Annual source energy

consumption

(quad/year)

Annual source energy

savings vs. baseline

(quad/year)

Baseline fan motors 7.2 × 109 0.077

Q-Sync fan motors 2.3 × 109 0.025 0.053

11

5. EFFECTS OF FAN MOTOR POWER FACTOR

The analysis presented in Section 4.1 estimates only the “real” energy consumed at the site by the

various types of evaporator fan motors. However, given that Q-Sync fan motors exhibit a significantly

higher power factor than EC and shaded-pole or PSC motors, it is expected that, through the

implementation of Q-Sync motors, utility companies will realize additional “apparent” energy savings at

their power plants beyond the “real” energy savings at the sites. This additional apparent energy savings

at the power plant should encourage utility companies to offer incentive programs for retrofitting Q-Sync

motors in place of EC and shaded-pole or PSC motors.

The “real” power, P, consumed by evaporator fan motors—that is, the power that produces useful

work—is the power that would be measured at the site by a utility power meter. The analysis presented in

Section 4.1 uses this “real” power to determine the total site energy consumption due to operation of

evaporator fan motors. However, electric motors also require reactive power, Q, to operate. The reactive

power does not do any useful work, but it provides the magnetic field required to produce rotation of the

motor’s rotor. Reactive power is typically not measured at the site; however, the power plant must

provide the reactive power, in addition to the real power, for the motor to operate.

In a purely resistive AC circuit, voltage and current are perfectly in phase, and there is no reactive

power. All the power consumed by the resistive load is real power. On the other hand, AC circuits with

inductors and/or capacitors exhibit a phase difference between the voltage and the current; thus both real

and reactive power are required by the load. The vector sum of the real power, P, and the reactive power,

Q, is called the apparent power, S. Thus, the power plant must supply this apparent power for the motor to

operate. The ratio between real power and apparent power is defined as the power factor, PF. Real power,

reactive power, apparent power and power factor are related as follows:

𝑆2 = 𝑃2 + 𝑄2 (1)

𝑃𝐹 =𝑃

𝑆=

𝑃

𝑉𝑟𝑚𝑠𝐼𝑟𝑚𝑠

where Vrms is the root-mean-square voltage and Irms is the root-mean-square current.

For a resistive load (such as an electric heating element or an incandescent light bulb), the real and

apparent power are equal since there is no reactive power; thus the power factor is one. However, for an

inductive load (such as an induction motor), both real power and reactive power are required; therefore,

real power is less than apparent power and the resulting power factor is less than one.

For the same real power output, a load with a low power factor requires more current than a load with

a high power factor. Thus Q-Sync fan motors, with their high power factor, will consume less current than

motors with a lower power factor. The lower current draw of the Q-Sync motors means reduced

generation and transmission costs for the utility company.

The reduction in apparent power generation at the power plant due to evaporator fan motor retrofits

can be estimated using the power factors of the existing 9–12 W commercial refrigeration evaporator fan

motors and the Q-Sync fan motors given in Table 1.

As discussed in Section 4.1 and shown in Table 3, for the baseline case of all shaded-pole and EC

motors, the total site electricity consumption is estimated to be 7.2×109 kWh per year. Dividing by

8760 hours per year, the instantaneous real power required is 0.82×109 W. As shown in Table 1, the

power factor for the baseline case of all shaded-pole and EC motors is assumed to be 0.601. Dividing the

instantaneous real power by this power factor results in an instantaneous apparent power of 1.4×109 VA.

The current required to supply this instantaneous apparent power can be calculated as follows:

𝐼𝑟𝑚𝑠 =𝑃

𝑉𝑟𝑚𝑠𝑃𝐹=

𝑆

𝑉𝑟𝑚𝑠 . (2)

12

Assuming Vrms = 120 V, electric utility companies would need to supply 11×106 A of current to the grid to

provide the instantaneous apparent power required by the baseline case of all shaded-pole and EC motors.

In contrast, as discussed in Section 4.1, if all currently installed fan motors were retrofitted with Q-

Sync fan motors, the total site electricity consumption would be estimated at 2.3×109 kWh per year.

Dividing by 8760 hours per year, the instantaneous real power required would be 0.26×109 W. As shown

in Table 1, the power factor for the Q-Sync motor is 0.936. Dividing the instantaneous real power by this

power factor results in an instantaneous apparent power of 0.28×109 VA. To provide this instantaneous

apparent power required by the Q-Sync motors, electric utility companies would need to supply

2.3×106 A of current to the grid.

Thus, comparing the baseline case of all shaded-pole and EC motors with an installed base of Q-Sync

motors, it can be seen that utilities would be required to supply 80% less apparent power and 80% less

current for Q-Sync motors compared with the baseline combination of shaded-pole and EC motors. This

would amount to significant savings for the utilities. Additional savings could be possible from a

reduction in transmission line investments or related maintenance due to the lower levels of delivered

current.

13

6. CONCLUSIONS

In this paper, various existing 9–12 W fan motor technologies were discussed: shaded-pole, PSC, and

EC motors. Furthermore, a new synchronous motor technology, the Q- Sync motor developed by QM

Power Inc. was discussed.

A field demonstration project was described wherein a side-by-side comparison is being conducted in

a 16 ft medium-temperature vertical multi-deck refrigerated display case at a Hy-Vee Supermarket

located in the Kansas City metropolitan area. Two 12 W Q-Sync motors are being compared with two

existing 12 W EC motors. The initial results show that compared with the EC motor, the Q-Sync motor

power consumption is 27.4% lower and the current draw is 53.3% lower. Thus the Q-Sync motor

efficiency is 73.1% versus 53.1% for the EC motor. Furthermore, the Q-Sync motor power factor is 0.936

compared with 0.601 for the existing EC motor.

Based on these preliminary test data, potential site and source energy savings associated with

retrofitting the existing installed base of 9–12 W commercial refrigeration evaporator fan motors with

Q-Sync fan motors was estimated. It was found that retrofitting the installed base with Q-Sync motors

would produce a 68% site energy savings, or 4.9×109 kWh/year (0.017 quad/year). This would result in

an annual cost savings of $516 million and reduce the annual CO2 equivalent emissions by 8.1×109 lb.

This amounts to a source energy savings of 0.053 quad per year.

Finally, the effects of fan motor power factor were discussed, including the relationship between real,

reactive, and apparent power. It was shown that Q-Sync motors, with their high power factors, will

consume less current than motors with a lower power factor. Comparing an installed base of Q-Sync

versus the baseline case of shaded-pole and EC motors, it can be seen that utilities would be required to

supply 80% less apparent power and 80% less current for Q-Sync motors than for the baseline

combination of shaded-pole and EC motors. This would amount to significant savings for the utilities.

This paper has focused on evaporator fan motors for commercial refrigeration equipment and

beverage vending machines. However, there are other applications where similar results could be

achieved, such as evaporator and condenser fans in domestic refrigerators/freezers; walk-in

coolers/freezers; and commercial and residential heating, ventilating, and air-conditioning systems. The

installed base of fan motors in these applications collectively numbers in the hundreds of millions. As

shown in Table 5, DOE BTO estimates that the annual source energy consumption of these fans is

approximately 2.3 quads (NCI 2013). Thus these applications consume significantly more electricity than

the 9–12 W motors that are the subject of this report—nearly 30 times as much source energy. Therefore,

it is possible that a broader upgrade to Q-Sync fan motors could reduce source energy consumption by as

much as one quad or more, with proportional environmental benefits.

14

Table 5. Annual source energy consumption of fans in residential and

commercial buildings (NCI 2013)

Fan application Primary energy (10

12

Btu/year)

Residential Buildings

CAC/HP outdoor fan 227.2

Furnace fan 442.9

RAC condenser fan 16.4

Dehumidifier condenser fan 8.6

Refrigerator/freezer condenser fan 46.5

Refrigerator/freezer evaporator fan 39.2

Commercial Buildings

PTAC indoor fan 11.9

PTAC outdoor fan 7.9

SPVAC indoor fan 1.8

SPVAC outdoor fan 1.2

CUAC indoor fan—small 86.0

CUAC indoor fan—medium 47.9

CUAC indoor fan—large 11.2

CUAC outdoor fan—small 86.0

CUAC outdoor fan—medium 47.9

CUAC outdoor fan—large 11.2

Exhaust fan 468.6

Room fan coil 9.7

AHU 492.6

Cooling tower fan 37.9

CRE condenser fan 37.7

BVM condenser fan 60.2

WICF condenser fan 39.9

WICF evaporator fan 39.9

ACIM condenser fan 11.8

Total: 2292.1

CAC = central air conditioner; HP = heat pump; RAC = room air conditioner; PTAC = packaged terminal

air conditioner; SPVAC = single packaged vertical air conditioner; CUAC = commercial unitary air

conditioner; AHU = air-handling unit; CRE = commercial refrigeration equipment; BVM = beverage

vending machine; WICF = walk-in cooler/freezer; AICM = automatic commercial ice maker

15

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